Induction of a Preferred Twist in a Biphenyl Core by Stereogenic Centers: A Novel Approach to the Absolute Configuration of 1,2- and 1,3-Diols

A quick, simple, and reliable method to assign the absolute configuration of 1,2- and 1,3-diols: all that is needed is to measure the CD sign of the A band (250 nm) of their biphenyldioxolanes 1 (n=0, 1). The chirality of the diol induces a preferred sense of twist in the biphenyl moiety (R,R→M and S,S→P), and a positive A band (a probe of M twist) reveals an R or R,R configuration of the diol.